AFTER 10 YEARS, HURRICANE ANDREW GAINS STRENGTH
August 21 , 2002 — In the record books, it’s still one of America’s costliest hurricanes, and today NOAA scientists announced Hurricane Andrew was even stronger than originally believed when it made landfall in south Florida 10 years ago this week. Based on new research, scientists upgraded the storm from a Category 4, to a Category 5, the highest on the Saffir-Simpson Hurricane Scale. (Click NOAA satellite image for larger view of Hurricane Andrew taken August 23, 1992.)
In their re-analysis of Hurricane Andrew’s maximum sustained surface-wind speeds, the NOAA National Hurricane Center Best Track Committee, a team of hurricane experts, concluded winds were 165 mph—20 mph faster than earlier estimated—as the storm made landfall. Herbert Saffir, a structural engineer who co-designed the Saffir-Simpson Hurricane Scale, joined the committee as an observer and reviewed the team’s results.
The upgrade makes Andrew only the third Category 5 (wind speeds greater than 155 mph) hurricane on record to strike the continental United States. The other two Category 5 storms were the “Florida Keys 1935 Hurricane,” and Hurricane Camille in 1969.
is always some uncertainty in determining the maximum winds in a hurricane,
and Andrew is no exception,” said Max Mayfield, director of the
National Hurricane Center, a part of NOAA’s
National Weather Service. “Our previous estimate was 145 mph,
based on the science available in 1992. With advanced research techniques
and technology, we now estimate the winds were stronger.”
The National Hurricane Center has had an ongoing program to review the historical record of all storms. Scientists and other researchers note that society needs an accurate account of the frequency and intensity of past catastrophic events to best plan for the future.
“We have recently completed a review of a re-analysis of storms from 1851 to 1910,” said Colin McAdie, chairman of the National Hurricane Center’s Best Track Committee. This re-analysis effort was undertaken by a team led by Chris Landsea of NOAA’s Hurricane Research Division and supported by a grant from the NOAA Office of Global Programs.
Hurricane Andrew is one of the most significant cases studied. According to McAdie, scientific understanding of the wind structure in strong hurricanes has significantly increased since 1992. For Andrew, the Best Track Committee considered input from scientists at the HRD, including the “re-analysis team” and National Hurricane Center.
Since 1997, forecasters have used Global Positioning System dropwindsondes, a measuring device dropped from hurricane reconnaissance aircraft into the eyewall—the windiest part of the hurricane. The sonde system measures temperature, barometric pressure, water vapor and wind data every 15 feet on its way down.
method gave meteorologists an important glimpse into the true strength
of these devastating storms. The analyses of the dropwindsonde data indicated
that, on average, the maximum sustained surface-wind speed was about 90
percent of the wind speed measured at the 10,000-foot aircraft level flown
as Andrew approached south Florida. In 1992, Andrew’s wind speed
was estimated at 75 to 80 percent of the aircraft observations. The research
findings resulted in an increase in the estimated wind speeds of Hurricane
Andrew from 145 mph to 165 mph.
When Hurricane Andrew hit southeast Miami-Dade County, Fla., Aug. 24, 1992, flying debris in the storm’s winds knocked out most ground-based wind measuring instruments, and widespread power outages caused electric-based measuring equipment to fail. The winds were so strong many wind-measuring tools were incapable of registering the maximum winds. Surviving wind observations and measurements from aircraft reconnaissance, surface pressure, satellite analysis, radar, and distribution of debris and structural failures were used to estimate the surface winds.
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